swap_prefetch: Remove useless reference to HIGHMEM reserves.

HIGHMEM "reserves" are always zero. Remove the addition of the highmem
reserves.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.17-mm6/mm/swap_prefetch.c
===================================================================
--- linux-2.6.17-mm6.orig/mm/swap_prefetch.c	2006-07-03 13:47:22.656121359 -0700
+++ linux-2.6.17-mm6/mm/swap_prefetch.c	2006-07-04 08:30:07.805828891 -0700
@@ -277,8 +277,7 @@ static void examine_free_limits(void)
 
 		ns = &sp_stat.node[z->zone_pgdat->node_id];
 		idx = zone_idx(z);
-		ns->lowfree[idx] = z->pages_high * 3 +
-			z->lowmem_reserve[ZONE_HIGHMEM];
+		ns->lowfree[idx] = z->pages_high * 3;
 		ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;
 
 		if (z->free_pages > ns->highfree[idx]) {